Decorative member

ABSTRACT

A white decorative member comprising: a substrate; a primary plate layer having a thickness of at least 1 μm and covering the substrate, which is composed of Cu (alloy); an Sn--Cu--Pd alloy plate layer having a thickness of at least 0.2 μm and covering the primary plate layer, which comprises 10 to 20% by weight of Sn, 10 to 80% by weight of Cu and 10 to 50% by weight of Pd as essential components; and a finishing plate layer having a thickness of 0.2 to 5 μm, which is composed of at least one element selected from the group consisting of Pd, Rh and Pt. The decorative member of the present invention does not contain any Ni component, so that, when worn, it does not induce Ni allergy. Moreover, the decorative member which may have white, gold, black or multicolor being a combination of the above colors can be produced at lowered cost.

THE FIELD OF INVENTION

The present invention relates to a decorative member. More particularly,the present invention is concerned with a decorative member which mayhave white, gold, black or multicolor being a combination of the abovecolors and which, when worn, does not induce Ni allergy.

BACKGROUND ART

Exterior watch parts such as wristwatch case frames, back lids andbands, ornaments such as necklaces, bracelets, pierced earrings, fingerrings and earrings and spectacle frames are decorative members which arebrought into direct contact with the skin when worn. Most of thesedecorative members have a tone such as white gloss, golden gloss orblack gloss.

In the industrial manufacturing of these decorative members, the commonprocess is employed in which a coating layer with the above tones areformed on a substrate, for example, a substrate of a metal in accordancewith the wet or dry plating technique.

For example, in the manufacturing of a watch case with white gloss, thecommon process comprises the formation as a primary layer of a Ni platelayer having a thickness of about 2 to 3 μm on a surface of a substrateof brass or German silver and thereafter the formation as a finishinglayer of a Pd--Ni alloy plate layer having a thickness of about 2 to 3μm on the Ni plate layer, optionally followed by flash plating of Rh orPt on the above Pd--Ni alloy plate layer.

In the manufacturing of a decorative member with golden gloss, thecommon process comprises the formation of a Ni plate layer having athickness of about 2 to 3 μm on a surface of a substrate of, forexample, brass or German silver, thereafter the formation of a Pd--Nialloy plate layer having a thickness of about 2 to 3 μm on the Ni platelayer and finally the formation of a layer of, for example, 22 caratAu--Ni alloy plate or an Au plate layer having a thickness of about 1 to2 μm on the Pd--Ni alloy plate layer. Further, a golden decorativemember has been proposed which is produced by sequentially forming an Niplate layer and then a Pd--Ni alloy plate layer on a surface of asubstrate according to the wet plating technique and thereaftersequentially forming an about 0.1 to 10 μm thick TiN layer and Au orAu--Ni alloy layer in this order on the Pd--Ni alloy plate layeraccording to the dry plating technique such as sputtering or vacuumevaporation technique.

In the manufacturing of a decorative member with black gloss, the commonprocess comprises the formation of about 2 to 3 μm thick Ni plate layeror Cu--Ni--Cr alloy plate layer on a surface of a substrate of, forexample, brass or German silver and forming thereon an about 0.5 to 3 μmblack Ni plate layer or black Cr plate layer. Further, a blackdecorative member has been proposed which is produced by forming theabove Ni plate layer or Cu--Ni--Cr alloy plate layer on a surface of asubstrate according to the wet plating technique and forming thereon aTaC layer having a thickness of about 0.1 to 2 μm according to the PVDtechnique such as ion plating or sputtering technique.

However, all the above conventional white, golden and black decorativemembers contain Ni, so that they have the danger of inducing dermatitisbecause the Ni may be dissolved as free Ni in, for example, the sweatexcreted from the skin and brought into contact with the skin.

White, golden and black decorative members which do not contain Ni haverecently been proposed for suppressing the above Ni allergization.

For example, white decorative members are known which are produced byforming a Cu plate layer or an Sn--Cu alloy plate layer containing 30 to35% by weight of Sn in a thickness of at least 2 μm on a surface of asubstrate of, for example, brass and forming thereon a finishing layerof a Pd plate layer having a thickness of about 0.1 to 5 μm. Also, whitedecorative members are known which are produced by forming a flash platelayer of Rh or Pt on the above Pd plate layer.

Golden decorative members are known which are produced by first forminga Cu plate layer or a plate layer of Cu alloy such as the above Sn--Cualloy on a surface of a substrate of, for example, brass, andsubsequently forming a Pd plate layer thereon and thereafter forming anAu plate layer or a plate layer of Au alloy not containing Ni, such asAu--Fe alloy, on the Pd plate layer.

Also, golden decorative members are known which are produced bysequentially forming an about 0.1 to 10 μm thick TiN layer and a layerof Au per se or Au alloy not containing Ni in this order on the above Pdplate layer according to the dry plating technique.

Black decorative members not containing any Ni component are known whichare produced by forming the above TaC layer directly on the above Pdplate layer according to the dry plating technique.

All the above decorative members do not contain any Ni component, sothat, when worn so as to be brought into contact with the skin, they donot induce Ni allergy.

However, these decorative members, without exception, form a plate layerfrom Pd which is an expensive noble metal, so that the product costthereof is inevitably very high.

Thus, efforts are being made to use a plate layer of Pd alloy in placeof the plate layer of Pd per se for reducing the relative content of Pdin the plate layer to thereby lower the whole product cost thereof.

A known example of the above plate layer of Pd alloy is a plate layer ofSn--Cu--Pd alloy. However, this plate layer of Sn--Cu--Pd alloy isunsatisfactory in the reduction of product cost because the Pd contentthereof is as conspicuously high as about 50 to 99% by weight.

In the above situation, the inventors made investigations on Sn--Cu--Pdalloy plate layers having a low Pd content and developed a method ofplating an Sn--Cu--Pd ternary alloy composed of 10 to 20% by weight ofSn, 10 to 80% by weight of Cu and 10 to 50% by weight of Pd and aplating bath for use in this method. These are described in JapanesePatent Application No. 5(1993)-80844.

The Sn--Cu--Pd alloy plate layer proposed therein has a low density ascompared with that of a plate layer of pure Pd and, for example, whencompared in plate layers of the same thicknesses, the Sn--Cu--Pd alloyplate layer has its Pd content reduced by about 60%, so that the productcost can be lowered. The Sn--Cu--Pd alloy plate layer has excellentcorrosion resistance and is furnished with excellent specular gloss.

The object of the present invention is to provide a decorative memberwhich may have white, gold, black or a multicolor combination of theabove colors and which does not induce Ni allergy and can be produced atlowered cost, by utilizing the above excellent properties of theSn--Cu--Pd alloy plate layer.

DISCLOSURE OF THE INVENTION

The white decorative member of the present invention comprises asubstrate; a primary plate layer having a thickness of at least 1 μm andcovering a surface of the substrate, the above primary plate layer beingcomposed of a Cu plate layer or Cu alloy plate layer; an Sn--Cu--Pdalloy plate layer having a thickness of at least 0.2 μm and covering asurface of the primary plate layer, the above Sn--Cu--Pd alloy platelayer comprising 10 to 20% by weight of Sn, 10 to 80% by weight of Cuand 10 to 50% by weight of Pd as essential components; and a finishingplate layer having a thickness of 0.2 to 5 μm and covering theSn--Cu--Pd alloy plate layer, the above finishing plate layer beingcomposed of at least one element selected from the group consisting ofPd, Rh and Pt.

The golden decorative member of the present invention (hereinafterreferred to as "the first golden decorative member") comprises asubstrate; a primary plate layer having a thickness of at least 1 μm andcovering a surface of the substrate, the above primary plate layer beingcomposed of a Cu plate layer or Cu alloy plate layer; an Sn--Cu--Pdalloy plate layer having a thickness of at least 0.2 μm and covering asurface of the primary plate layer, the above Sn--Cu--Pd alloy platelayer comprising 10 to 20% by weight of Sn, 10 to 80% by weight of Cuand 10 to 50% by weight of Pd as essential components; and a finishingplate layer having a thickness of 0.2 to 5 μm and covering theSn--Cu--Pd alloy plate layer, the above finishing plate layer beingcomposed of an Au plate layer or an Au alloy plate layer which does notcontain Ni.

The golden decorative member of the present invention (hereinafterreferred to as "the second golden decorative member") comprises asubstrate; a primary plate layer having a thickness of at least 1 μm andcovering a surface of the substrate, the above primary plate layer beingcomposed of a Cu plate layer or Cu alloy plate layer; an Sn--Cu--Pdalloy plate layer having a thickness of at least 0.2 μm and covering asurface of the primary plate layer, the above Sn--Cu--Pd alloy platelayer comprising 10 to 20% by weight of Sn, 10 to 80% by weight of Cuand 10 to 50% by weight of Pd as essential components; a TiN layerhaving a thickness of 0.1 to 10 μm and covering a surface of theSn--Cu--Pd alloy plate layer; and a finishing plate layer having athickness of 0.05 to 0.5 μm and covering the TiN layer, the abovefinishing layer being composed of Au alone or an Au alloy which does notcontain Ni.

The black decorative member of the present invention comprises asubstrate; a primary plate layer having a thickness of at least 1 μm andcovering a surface of the substrate, the above primary plate layer beingcomposed of a Cu plate layer or Cu alloy plate layer; an Sn--Cu--Pdalloy plate layer having a thickness of at least 0.2 μm and covering asurface of the primary plate layer, the above Sn--Cu--Pd alloy platelayer comprising 10 to 20% by weight of Sn, 10 to 80% by weight of Cuand 10 to 50% by weight of Pd as essential components; a Ti layer havinga thickness of 0.2 to 10 μm and covering a surface of the Sn--Cu--Pdalloy plate layer; and a finishing layer having a thickness of 0.5 to2.0 μm and covering the Ti layer, the above finishing layer beingcomposed of TiNCO.

The multicolored decorative member of the present invention comprises asubstrate; a primary plate layer having a thickness of at least 1 μm andcovering a surface of the substrate, the above primary plate layer beingcomposed of a Cu plate layer or Cu alloy plate layer; an Sn--Cu--Pdalloy plate layer having a thickness of at least 0.2 μm and covering asurface of the primary plate layer, the above Sn--Cu--Pd alloy platelayer comprising 10 to 20% by weight of Sn, 10 to 80% by weight of Cuand 10 to 50% by weight of Pd as essential components; a finishing layerhaving a thickness of 0.2 to 5.0 μm and covering a surface of theSn--Cu--Pd alloy plate layer, the above finishing layer being composedof a material selected from the group consisting of Pd, Rh, Pt, Au, anAu alloy and TiNCO; and a partial finishing layer covering part of asurface of the finishing layer, the above partial finishing layer beingcomposed of a material which is different from that of the finishinglayer and having a tone which is different from that of the finishinglayer.

In the decorative members of the present invention, none of theconstituent materials thereof contains Ni, so that they do not sufferfrom dissolution of free Ni and that, when worn so as to be brought intocontact with the skin, the decorative members do not induce Ni allergy.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a sectional view of the layer structure of white decorativemember A according to the present invention;

FIG. 2 is a sectional view of the layer structure of golden decorativemember B according to the present invention;

FIG. 3 is a sectional view of the layer structure of another goldendecorative member B' according to the present invention;

FIG. 4 is a sectional view of the layer structure of a further othergolden decorative member C according to the present invention;

FIG. 5 is a sectional view of the layer structure of still a furtherother golden decorative member C' according to the present invention;

FIG. 6 is a sectional view of the layer structure of black decorativemember D according to the present invention;

FIG. 7 is a sectional view of the layer structure of multicoloreddecorative member E1 according to the present invention;

FIG. 8 is a sectional view showing the state of white decorative memberA of FIG. 1 having a plate layer of Au or Au alloy formed on itssurface;

FIG. 9 is a sectional view showing the state of plate layer of FIG. 8having a pattern mask formed thereon;

FIG. 10 is a sectional view showing the state of plate layer having beenremoved at area other than that in which the pattern mask has beenformed in FIG. 9; and

FIG. 11 is a sectional view of the layer structure of anothermulticolored decorative member E2 according to the present invention.

In the figures, numeral 1 denotes a substrate (brass), numeral 2 aprimary plate layer (Cu or Cu alloy), numeral 3 an Sn--Cu--Pd alloyplate layer, numeral 4 a finishing plate layer (Pd, Rh or Pt), numeral 5a finishing plate layer (Au or Au alloy), numeral 6 a Pd plate layer,numeral 7 a TiN layer formed according to the dry plating technique,numeral 8 a finishing layer of Au or Au alloy formed according to thedry plating technique, numeral 9 a Ti layer formed according to the dryplating technique, numeral 10 a finishing layer of TiNCO formedaccording to the dry plating technique, and numeral 11 a pattern mask.

BEST MODE FOR CARRYING OUT THE INVENTION

First, the white decorative member A of the present invention will bedescribed with reference to FIG. 1.

Referring to FIG. 1, the substrate 1 consists of brass, and a surface ofthis substrate 1 is covered by a primary plate layer 2 having athickness of at least 1 μm, which is composed of a Cu plate layer or Cualloy plate layer. The primary plate layer 2 has a function of ensuringthe adhesion between the surface of the substrate 1 and the belowdescribed Sn--Cu--Pd alloy plate layer to thereby prevent peeling of theplate coating and improves the gloss of the substrate by virtue of theleveling property of the contained Cu. This primary plate layer 2 isformed by the wet plating technique.

The material of the substrate 1 is not limited to brass. It may be, forexample, copper, a copper alloy (e.g., red brass or phosphor bronze),zinc or a zinc alloy (e.g., Zn--Al alloy or Zn--Al--Cu alloy).

When the thickness of the primary plate layer 2 is smaller than 1 μm, abrittle intermetallic compound is formed between the primary plate layer2 and the substrate 1 (brass) at the time of the wet plating, so thatthe adhesion between the primary plate layer 2 and the surface of thesubstrate 1 is lowered. On the other hand, when the above thickness istoo large, not only is it of no use for the primary plate layer, butalso a plate strain is accumulated to an extreme extent with the resultthat a peeling phenomenon would be encountered. The thickness of thisprimary plate layer 2 is preferred to range from 1 to 5 μm.

When the primary plate layer 2 is formed of a Cu alloy, for example,Cu--Sn alloy, Cu--Sn--Zn alloy, Cu--Sn--Pb alloy or Cu--Sn--Cd alloy canbe used as the Cu alloy. Of these, Cu--Sn--Zn alloy comprising 20 to 40%by weight of Sn, 1 to 10% by weight of Zn and a balance of Cu canpreferably be used.

When the substrate 1 is composed of brass, the primary plate layer 2formed of the above Cu alloy enables desirable adhesion between thesubstrate 1 and the below described Sn--Cu--Pd alloy plate layer becausethe primary plate layer 2 has high affinity with the Zn component of thesubstrate 1 and with the Sn component of the Sn--Cu--Pd alloy platelayer.

In this structure, when the Sn content of the Cu alloy is lower than 20%by weight, the primary plate layer has poor corrosion resistance. On theother hand, when the Sn content is larger than 40% by weight, theprimary plate layer 2 has intense strain, so that it has a greatertendency to be peeled from the surface of the substrate 1. When it isattempted to produce a primary plate layer composed of a Cu alloy whoseZn content is lower than 1% by weight, the Zn content of the platingbath composition is so low that the effect of lessening a differencebetween Cu and Sn deposition potentials at the time of plating isweakened with the result that realizing desirable gloss becomesdifficult during low current operation or high current operation.Further, when the Zn content of the Cu alloy exceeds 10% by weight, theprimary plate layer has poor corrosion resistance. When it is attemptedto produce a primary plate layer whose Zn content exceeds 10% by weight,the amount of Cu precipitated at the time of plating becomes largethereby unfavorably rendering the entirety of the primary plate layeryellowish.

The above alloy composition can be easily realized by regulating thecomposition of the bath employed in the wet plating.

Subsequently, the Sn--Cu--Pd alloy plate layer 3 is formed on thesurface of this primary plate layer 2 according to the wet platingtechnique.

This Sn--Cu--Pd alloy plate layer 3 is formed by the method described inJapanese Patent Application No. 5(1993)-80844 and the compositionthereof comprises 10 to 20% by weight of Sn, 10 to 80% by weight of Cuand 10 to 50% by weight of Pd as essential components.

When the Sn content of the above Sn--Cu--Pd alloy plate layer is lowerthan 10% by weight, not only is the surface gloss of the Sn--Cu--Pdalloy plate layer deteriorated but also the corrosion resistance thereofbecomes poor. The surface gloss of the Sn--Cu--Pd alloy plate layer 3 isalso poor when the Sn content thereof exceeds 20% by weight. Thus, theSn content is set to fall in the above range. It is preferred that thisSn content of the Sn--Cu--Pd alloy plate layer 3 range from 13 to 19% byweight, especially, 16 to 18% by weight.

When the Cu content is lower than 10% by weight, the Sn--Cu--Pd alloyplate layer 3 has poor surface gloss. The surface gloss is also poorwhen the Cu content of the Sn--Cu--Pd alloy plate layer exceeds 80% byweight. Furthermore, the Cu content exceeds 80% by weight, the corrosionresistance of the plate layer is deteriorated. Therefore, the Cu contentis set to fall in the above range. It is preferred that the Cu contentof the Sn--Cu--Pd alloy plate layer 3 range from 35 to 65% by weight,especially, 43 to 45% by weight.

When the Pd content is lower than 10% by weight, the Sn--Cu--Pd alloyplate layer 3 has poor surface gloss. The surface gloss is also poorwhen the Pd content of the Sn--Cu--Pd alloy plate layer exceeds 50% byweight. Furthermore, the Pd content exceeds 50% by weight, not only isthe corrosion resistance of the plate layer deteriorated but also theproduct cost is increased. Therefore, the Pd content is set to fall inthe above range. It is preferred that the Pd content of the Sn--Cu--Pdalloy plate layer 3 range from 25 to 45% by weight, especially, 37 to40% by weight.

In particular, an Sn--Cu--Pd alloy plate layer comprising 16 to 18% byweight of Sn, 43 to 45% by weight of Cu and 37 to 40% by weight of Pd ishighly advantageous in that the content of expensive Pd in the platelayer is so low that the product cost can be reduced, that the surfacegloss and corrosion resistance are excellent, that the effect ofenhancing the adhesion between the above primary plate layer 2 and thebelow described finishing plate layer is striking and that the heatresistance is high.

The thickness of this Sn--Cu--Pd alloy plate layer 3 is set at 0.2 μm orgreater. The reason is that, when this thickness is smaller than 0.2 μm,zones of poor throwing power occur at the time of plating and at thosezones the corrosion resistance is deteriorated. This Sn--Cu--Pd alloyplate layer 3 is preferred to have a thickness of 0.2 to 10 μm.

Finally, the finishing plate layer 4 composed of one or at least twoelements selected from the group consisting of Pd, Rh and Pt is formedso as to cover the surface of the Sn--Cu--Pd alloy plate layer 3according to the wet plating technique, thereby obtaining the whitedecorative member A of the present invention.

The thickness of this finishing plate layer 4 is set at 0.2 to 5 μm. Thereason is that, when this thickness is smaller than 0.2 μm, the tone ofwhite gloss as a decorative member becomes defective and that, when thethickness is larger than 5 μm, the improvement of tone reachessaturation and only the wasting of the expensive noble metal is invitedto thereby incur an increase of product cost. From the viewpoint ofsecuring the tone of economically desirable white gloss, it is preferredthat the thickness of the finishing plate layer 4 range from 0.2 to 3μm.

The thickness of this finishing plate layer 4 can be reduced by causingthe above Sn--Cu--Pd alloy plate layer 3 to have a thickness asrelatively large as 4 to 5 μm with the result that desirable white glosstone can be developed on the surface thereof. Thus, economic advantageis attained.

In this white decorative member A, none of the substrate 1 andindividual plate layers contains Ni, so that, when brought into contactwith the sweat excreted from the skin, the white decorative member Adoes not suffer from dissolution of free Ni and does not induce Niallergy. The Sn--Cu--Pd alloy plate layer 3 in its entirety is endowedwith white gloss and has excellent corrosion resistance. Therefore, forexample, even if the outermost finishing plate layer 4 is damaged, thedecorative member A can continue to exhibit white gloss tone on itssurface for a prolonged period of time.

The hardness (Hv) of the Sn--Cu--Pd alloy plate layer 3 is as high asabout 250 to 350, so that, for example, even if the finishing platelayer 4 is damaged, the damaging of the substrate 1 thereby caneffectively be checked.

Now, the first golden decorative member B of the present invention willbe described referring to FIG. 2.

This golden decorative member B has the same layer structure as that ofthe white decorative member A, except that the finishing plate layer 4of the white decorative member A as shown in FIG. 1 is replaced by afinishing plate layer 5 with golden gloss which is composed of an Auplate layer or an Au alloy plate layer not containing Ni.

The above finishing plate layer 5 is formed according to the wet platingtechnique, and the thickness thereof is set at 0.2 to 5 μm.

The reason is that, when the thickness of the finishing plate layer 5 issmaller than 0.2 μm, the white tone of the Sn--Cu--Pd alloy plate layer3 positioned as a sublayer is exposed to thereby cause the tone ofgolden gloss as a golden decorative member to become defective and that,when the thickness is larger than 5 μm, the improvement of golden glosstone reaches saturation and only the wasting of the expensive Au iscaused thereby incurring an increase of product cost.

When this finishing plate layer 5 is formed of an Au alloy, for example,Au--Fe, Au--Pd, Au--Pt, Au--Sn, Au--Ag, Au--In, Au--Cu, Au--Pd--Fe andAu--In--Fe alloys which do not contain Ni are employed as the Au alloy.

This golden decorative member may have a layer structure B' in which aPd plate layer 6 is interposed between the Sn--Cu--Pd alloy plate layer3 and the finishing plate layer 5 according to the wet platingtechnique, as shown in FIG. 3.

This layer structure B' is desirable because the adhesion between theSn--Cu--Pd alloy plate layer 3 and the finishing plate layer 5 isenhanced as compared with that of the layer structure of FIG. 2.

When the thickness of the Pd plate layer 6 is too large, an increasedproduct cost is invited. On the other hand, when the thickness is toosmall, the above effect of enhancing the adhesion cannot be fullyexerted. The thickness of the Pd plate layer 6 is preferred to rangefrom 0.2 to 1 μm.

The second golden decorative member C of the present invention will bedescribed below referring to FIG. 4.

This golden decorative member C has the same layer structure as that ofthe golden decorative member B, except that the golden finishing platelayer 5 of the golden decorative member B as shown in FIG. 2 is replacedby a finishing layer 8 composed of Au per se or an Au alloy notcontaining Ni and that a TiN layer 7 formed according to the dry platingtechnique is interposed between this finishing layer 8 and theSn--Cu--Pd alloy plate layer 3.

This TiN layer 7 has golden gloss and has excellent abrasion resistance,so that, even when the finishing layer 8 formed on the TiN layer 7 isworn to thereby disenable the exhibition of golden gloss, the TiN layer7 instead exhibits golden gloss to thereby play the role of securing thefunction of the golden decorative member for a prolonged period of time.Further, even if the thickness of the finishing layer 8 composed of Auper se or an Au alloy is drastically cut, the resultant decorativemember can secure golden ornamentation on its surface to thereby enablereduction of the product cost.

The thickness of this TiN layer 7 is set at 0.1 to 10 μm. When thisthickness is smaller than 0.1 μm, satisfactory abrasion resistancecannot be retained with the result that the white gloss of theSn--Cu--Pd alloy plate layer 3 positioned thereunder is exposed within ashort period of time. On the other hand, when this thickness is largerthan 10 μm, the TiN layer 7 per se suffers from clouding with the resultthat not only is the appearance thereof deteriorated but also anincrease of the product cost is invited. The thickness of this TiN layer7 is preferred to range from 0.2 to 0.3 μm.

The thickness of the finishing layer 8 formed on the TiN layer 7 is setat 0.05 to 0.5 μm. When this thickness is smaller than 0.05 μm, thethrowing power is so unsatisfactory that the TiN layer 7 as a sublayeris exposed. On the other hand, when the thickness is larger than 0.5 μm,the improvement of golden gloss tone reaches saturation and only thewasting of the expensive Au is invited. The thickness of the finishinglayer 8 is preferred to range from 0.2 to 0.3 μm.

Both the TiN layer 7 and the finishing layer 8 are formed according tothe conventional dry plating technique. The dry plating techniquesuitably employed is, for example, the sputtering, ion plating or vacuumevaporation technique.

In this golden decorative member C, none of the constituent memberscontains Ni, so that dissolution of free Ni does not occur at all whenthe golden decorative member C is brought into contact with the sweatexcreted from the skin and no persons who wear it suffer from Niallergy.

When the soft finishing layer 8 is abraded by the wear of the goldendecorative member C to thereby cause the golden gloss of the finishinglayer 8 to disappear, the highly abrasion resistant TiN layer 7positioned thereunder can continue to exhibit golden gloss for aprolonged period of time.

Further, even when the finishing layer 8 and the TiN layer 7 are damagedto thereby cause, for example, the sweat excreted from the skin topenetrate into the golden decorative member C, the corrosion resistanceof the golden decorative member C is secured for a prolonged period oftime because of the excellent corrosion resistance of the Sn--Cu--Pdalloy plate layer 3 positioned thereunder.

This golden decorative member may have a layer structure C' in which aPd plate layer 6 is interposed between the Sn--Cu--Pd alloy plate layer3 and the TiN layer 7 according to the wet plating technique, as shownin FIG. 5.

This layer structure C' is desirable because the adhesion between theSn--Cu--Pd alloy plate layer 3 and the TiN layer 7 is enhanced ascompared with that of the layer structure of FIG. 4.

When the thickness of the Pd plate layer 6 is too large, an increase ofproduct cost is invited. On the other hand, when the thickness is toosmall, the above effect of enhancing the adhesion cannot be fullyexerted. The thickness of the Pd plate layer 6 is preferred to rangefrom 0.2 to 1 μm.

The black golden decorative member D of the present invention will bedescribed below referring to FIG. 6.

This black decorative member D has the same layer structure as that ofthe white decorative member A shown in FIG. 1, except that the finishingplate layer 4 of the white decorative member A is replaced by afinishing layer 10 of TiNCO formed according to the dry platingtechnique and that a Ti layer 9 formed according to the dry platingtechnique is interposed between the finishing layer 10 and theSn--Cu--Pd alloy plate layer 3.

The finishing layer 10 has black gloss and the hardness (Hv) thereofranges from 1000 to 1500. The abrasion resistance of the finishing layer10 is so high that the function of the black decorative member can becontinued to secure for a prolonged period of time.

The Ti layer 9 formed under the finishing layer 10 is capable of firmlybonding the finishing layer 10 to the Sn--Cu--Pd alloy plate layer 3.Because of the interposition of this Ti layer 9, the black decorativemember D is completely free from the problem of peeling of the blackfinishing layer 10 from the Sn--Cu--Pd alloy plate layer 3.

As long as carried under ordinary conditions, the black decorativemember D is free from the problem of peeling of the finishing layer 10even in the absence of the Ti layer 9, that is, even when the finishinglayer 10 is directly formed on the Sn--Cu--Pd alloy plate layer 3.

The thickness of this finishing layer 10 is set at 0.5 to 2.0 μm. Whenthis thickness is smaller than 0.5 μm, the finishing layer 10 isaffected by the tone of the Ti layer 9 and Sn--Cu--Pd alloy plate layer3 (both white) positioned thereunder to thereby render obtaining fairblack gloss difficult. On the other hand, when the thickness of thefinishing layer 10 is larger than 2.0 μm, the strain accumulation isintense at the formation of the finishing layer 10 with the result thatcracking of the finishing layer 10 may occur and that the workability atthe layer formation is lowered. The thickness of the finishing layer 10is preferred to range from 0.8 to 1.5 μm.

The thickness of the Ti layer 9 formed under the finishing layer 10 isset at 0.2 to 1.0 μm. When this thickness is smaller than 0.2 μm, theadhesion between the finishing layer 10 and the Sn--Cu--Pd alloy platelayer 3 is likely to lower. On the other hand, when the thickness of theTi layer 9 is larger than 1.0 μm, not only does the above effect ofenhancing the adhesion remain unchanged but also the workability at thelayer formation is lowered. The thickness of the Ti layer 9 is preferredto range from 0.4 to 0.8 μm.

Both the finishing layer 10 and the Ti layer 9 are formed according tothe dry plating technique. The dry plating technique suitably employedis, for example, the ion plating, sputtering or vacuum evaporationtechnique. In the formation of the finishing layer 10 with black gloss,suitable use is made of the method disclosed in Japanese PatentLaid-open Publication No. 63(1988)-161158.

The above description concerns the decorative members whose respectivesurfaces have white, golden and black glosses. In the present invention,a multi-colored decorative member whose surface has a combination of atleast two gloss tones can be produced by combining them.

That is, a surface having the tone of the finishing layer mixed with adifferent tone can be produced by forming on the Sn--Cu--Pd alloy platelayer 3 a finishing layer composed of a layer of any of Pd, Rh and Pt(all white), a layer of any of Au and an Au alloy (both golden) or alayer of TiNCO (black) and by subsequently forming a layer (for example,a layer of Pd, Rh or Pt, a layer of Au or an Au alloy or a layer ofTiNCO) covering part of a surface of this finishing layer, which has atone different from that of the finishing layer.

Of the multicolored decorative member varieties according to the presentinvention, for example, a decorative member E1 having a surface with twocolors of white and golden glosses will be described below withreference to FIG. 7.

This decorative member E1 is obtained by forming a pattern 5a of an Auplate layer or Au alloy plate layer so as to cover part of the surfaceof the finishing plate layer 4 of the white decorative member A shown inFIG. 1.

In the production of this decorative member E1, first, an Au or Au alloyplate layer 5 is formed so as to cover the entire surface of thefinishing plate layer 4 of the white decorative member A shown in FIG. 1(see FIG. 8).

Subsequently, referring to FIG. 9, a mask pattern 11 is formed on areasintended to be left intact of the surface of the plate layer 5 by thecustomary printing such as screen, pad or offset printing, brushing orphotoengraving. Thereafter, the member of FIG. 9 is immersed in acyanide-based Au stripping solution to thereby dissolve away the platelayer 5 at the areas other than the above areas covered by the maskpattern 11. Thus, referring to FIG. 10, the plate layer 5 at the areascovered by the mask pattern 11 of preselected pattern remains on theplate layer 4 with white gloss.

Thereafter, the mask pattern 11 is peeled off, thereby obtaining thedecorative member E1 with two colors of white and gold shown in FIG. 7.

FIG. 11 is a sectional view of another bicolored decorative member E2.In this bicolored decorative member E2, a pattern 5a of golden platelayer is formed on the finishing layer 10 of the black decorative memberD of FIG. 6 in the same manner as mentioned above with respect to thedecorative member E1. Thus, this decorative member E2 is a decorativemember with two colors of black and gold having a golden pattern formedon the surface with black gloss.

EXAMPLE Example 1

Layers were formed on a surface of a watch case of brass in thefollowing manner, thereby obtaining a white decorative member having thelayer structure of FIG. 1.

(1) Formation of Primary Plate Layer 2

    ______________________________________                                        Composition of plating bath:                                                    Na.sub.2 SnO.sub.3 · 3H.sub.2 O   60 g/lit.,                         CuCN            20 g/lit.,                                                    K.sub.2 SO.sub.3 H          10 g/lit.,                                        KCN (free)      30 g/lit.,                                                    KOH             60 g/lit.,                                                    Zn(CN).sub.2           5 g/lit.                                               Plating conditions:                                                           bath temperature      50° C.,                                          current density       2.4 A/dm.sup.2,                                         pH                    12.5,                                                   deposition rate        0.33 μm/min, and                                    time                  10 min.                                               ______________________________________                                    

A Cu--Sn--Zn alloy plate layer 2 having a thickness of about 3 μm wasformed on the surface of the watch case.

(2) Formation of Sn--Cu--Pd Alloy Plate Layer

An Sn--Cu--Pd alloy plate layer 3 was formed on the Cu--Sn--Zn alloyplate layer 2 under the following conditions.

    ______________________________________                                        Composition of plating bath:                                                    Na.sub.2 SnO.sub.3 · 3H.sub.2 O    60 g/lit.                         (26.7 g/lit. in terms of Sn),                                                 CuCN            20 g/lit.                                                     (14.2 g/lit. in terms of Cu),                                                 K.sub.2 SO.sub.3 H          10 g/lit.,                                        KCN (free)      30 g/lit.,                                                    KOH             60 g/lit.,                                                    K.sub.2 Pd(CN).sub.4.3H.sub.2 O  30 g/lit.                                    (9.3 g/lit. in terms of Pd).                                                  Plating conditions:                                                           bath temperature       50 to 55° C.,                                   current density        2.0 A/dm.sup.2,                                        current efficiency     47.8%,                                                 pH                     12.5 to 13,                                            deposition rate        0.33 μm/min, and                                    time                   9 min.                                               ______________________________________                                    

A plate layer of about 3 μm in thickness, about 300 in hardness (Hv) and9.6 g/cm³ in density was formed. A simple quantitative analysis of thecomposition of this plate layer was carried out by the use of a scanningelectron micrograph and an X-ray microanalyzer, and it was found thatthe plate layer was composed of a ternary alloy consisting of 17.12% byweight of Sn, 44.22% by weight of Cu and 38.66% by weight of Pd.

(3) Formation of Finishing Plate Layer 4

A plate layer 4 was formed on the Sn--Cu--Pd alloy plate layer 3 underthe following conditions. Plating bath: Pallabright-SSS (trade name)produced by Japan Pure Chemical Co., Ltd.

    ______________________________________                                        Plating conditions:                                                             bath temperature       55                                                                       ° C.,                                                current density        1.5 A/dm.sup.2,                                        pH                     7.6,                                                   deposition rate         0.33 μm/min, and                                   time                   6 min.                                               ______________________________________                                    

A Pd plate layer 4 with white gloss having a thickness of about 2 μm wasformed.

The thus obtained watch case with white gloss (white decorative member)was immersed in an artificial sweat (40° C.) containing 9.9 g/lit. ofsodium chloride, 0.8 g/lit. of sodium sulfide, 7.1 g/lit. of urea, 0.19ml/lit. of aqueous ammonia, 0.2 g/lit. of saccharose and 0.8 ml/lit. oflactic acid (50%) for 24 hr.

No surface discoloration occurred, thereby attesting to excellentcorrosion resistance.

Further, this watch case with white gloss was subjected to a heatingtest in which it was allowed to stand still at 200° C. for 5 hr. Noplate peeling was observed.

Example 2

Layers were formed on a surface of a watch case of brass in thefollowing manner, thereby obtaining a golden decorative member havingthe layer structure B of FIG. 2.

A primary plate layer 2 and an Sn--Cu--Pd alloy plate layer 3 wereformed in the same manner as in Example 1.

A plating bath of 4.0 in pH containing 10 g/lit. of Au, 0.3 g/lit. ofPt, 100 g/lit. of citric acid and 50 g/lit. of sodium citrate wasprepared, and a wet plating was performed for 15 min under conditionssuch that the bath temperature was 40° C. and the current density was1.0 A/dm². Thus, an Au--Pt alloy plate layer 5 having a thickness of 3.6μm was formed on the above Sn--Cu--Pd alloy plate layer 3.

The resultant watch case with golden gloss (golden decorative member)exhibited substantially the same corrosion resistance and heatresistance as in Example 1.

Example 3

Layers were formed on a surface of a watch case of brass in thefollowing manner, thereby obtaining a golden decorative member havingthe layer structure B' of FIG. 3.

First, a primary plate layer 2 was formed under the same conditions asin Example 1. An Sn--Cu--Pd alloy plate layer 3 having a thickness of2.5 μm was formed thereon under the same conditions as in Example 1,except that the plating time was 7.5 min. Further, a Pd plate layer 6having a thickness of 0.5 μm was formed thereon under the sameconditions as in the formation of finishing plate layer of Example 1,except that the plating time was 1 min. Finally, an Au--Pt alloy platelayer 5 was formed on the Pd plate layer 6 under the same conditions asin Example 2.

The resultant watch case with golden gloss (golden decorative member)exhibited substantially the same corrosion resistance and heatresistance as in Example 1.

Example 4

A primary plate layer 2 and an Sn--Cu--Pd alloy plate layer 3 weresequentially formed on a surface of a watch case of brass under the sameconditions as in Example 1. Thereafter, a TiN layer 7 and a finishinglayer 8 were formed on the Sn--Cu--Pd alloy plate layer 3 under thefollowing conditions, thereby obtaining a golden decorative memberhaving the layer structure C of FIG. 4.

The member having the Sn--Cu--Pd alloy plate layer 3 formed was set inan ion plating apparatus. The interior of the apparatus was evacuatedand Ar gas was introduced thereinto so that the degree of vacuum of theapparatus was 1.0×10⁻³ Torr.

Then, a thermionic filament and a plasma electrode arranged in theapparatus were operated to generate Ar plasma. An ion bombardmentcleaning was performed for 10 min on the surface of the Sn--Cu--Pd alloyplate layer 3.

Thereafter, N₂ gas was introduced into the apparatus so as to maintainthe degree of vacuum in the apparatus at 2.0×10⁻³ Torr. While operatinga plasma gun disposed in the apparatus to generate plasma, Ti wasevaporated for 10 min, thereby forming a 0.5 μm thick TiN layer 7 on theabove Sn--Cu--Pd alloy plate layer 3.

The evaporation of Ti and the introduction of N₂ gas were terminated. AnAu--Fe alloy containing 6% by weight of Fe was evaporated, so that a 0.3μm thick Au--Fe alloy plate layer 8 was formed on the above TIN layer 7.

The thus obtained watch case with golden gloss (golden decorativemember) had a uniform specified golden tone satisfying color 1N-14defined in the Swiss Gold Plating Color Standards and the tone measuredby a color difference meter was L*80, a*1.0, b*15.0.

A 24 hr corrosion resistance test was conducted for the watch case withthe use of the same artificial sweat as in Example 1. No corrosion anddiscoloration were observed.

Moreover, an Ni reaction detecting test was conducted by wiping thewatch case with a gauze impregnated with a dimethylglyoxime alcoholsolution. No red coloration occurred and no free Ni was detected.

Example 5

An Sn--Cu--Pd alloy plate layer 3 was formed in the same manner as inExample 4, and the thickness thereof was caused to be the same 2.5 μm asin Example 3. A 0.5 μm thick Pd plate layer 6 was formed thereon underthe same conditions as in Example 3. A 0.5 μm thick TiN layer 7 and a0.3 μm thick Au--Fe alloy plate layer 8 were sequentially formed on theabove Pd plate layer 6 in the same manner as in Example 4. Thus, agolden decorative member having the layer structure C' of FIG. 5 wasproduced.

A 48 hr corrosion resistance test was conducted for the above watch casehaving golden gloss with the use of the same artificial sweat as inExample 1. No corrosion and discoloration were observed.

Example 6

A primary plate layer 2 and an Sn--Cu--Pd alloy plate layer 3 weresequentially formed on a surface of a watch case of brass under the sameconditions as in Example 1. Thereafter, a Ti layer 9 and a finishinglayer of TiNCO 10 were formed on the Sn--Cu--Pd alloy plate layer 3under the following conditions, thereby obtaining a black decorativemember D having the layer structure of FIG. 6.

The member having the Sn--Cu--Pd alloy plate layer 3 formed was set in abell-jar of an ion plating apparatus. The interior of the bell-jar wasevacuated and Ar gas was introduced thereinto so that the degree ofvacuum of the bell-jar was in the range of 5×10⁻⁴ to 1×10⁻² Torr.

Then, a thermionic filament and a plasma electrode arranged in theapparatus were operated to generate Ar plasma. An ion bombardmentcleaning was performed for about 10 min on the surface of the Sn--Cu--Pdalloy plate layer 3.

Subsequently, the degree of vacuum of the bell-jar was adjusted so as tofall in the range of 3×10⁻⁴ to 1×10⁻² Torr, and metallic Ti as a vaporsource was irradiated with electron beam generated by a plasma gundisposed in the apparatus. The resultant Ti vapor and Ar gas wereionized in the plasma and an accelerating voltage of negative potential50 to 200 V was applied to the member. Thus, a Ti layer 9 of 0.5 μm inthickness was formed on the Sn--Cu--Pd alloy plate layer 3.

Thereafter, a mixture of N₂ gas and Ar gas containing 0.1 to 5.0% byvolume of O₂ and 0.1 to 2.0% by volume of CO was introduced in thebell-jar and feed/exhaust control was effected so that the degree ofvacuum of the bell-jar was maintained at 5×10⁻³ Torr.

Metallic Ti was irradiated with electron beam generated by the plasmagun to thereby produce Ti vapor and, simultaneously, a direct currentvoltage of 50 V was applied between the metallic Ti as a positiveelectrode and the member as a negative electrode so as to pass an ioniccurrent of SA for about 30 min.

Thus, a black finishing layer 10 of TiNCO having a thickness of about 1μm was formed on the Ti layer 9.

The obtained watch case (black decorative member) had a surface withglossy black tone and exhibited the same corrosion resistance and heatresistance as had by the white decorative member of Example 1. A 90°bending test was conducted. No peeling of the black finishing layer wasobserved at the surface, attesting to excellent adhesion with thesubstrate.

Example 7

A primary plate layer 2 and an Sn--Cu--Pd alloy plate layer 3 weresequentially formed on a surface of a watch case of brass under the sameconditions as in Example 1. Thereafter, a finishing plate layer 4 of Rhwas formed on the Sn--Cu--Pd alloy plate layer 3 and a partial finishingplate layer of Au--Pt alloy 5 was formed thereon in the followingmanner, thereby obtaining a multicolored decorative member having thelayer structure of FIG. 7.

The surface of the member having the Sn--Cu--Pd alloy plate layer 3formed was subjected to a wet plating under the following conditions:

    ______________________________________                                        plating bath composition:                                                                         2 g/lit. of Rh and 38                                                                        ml/lit. of H.sub.2 SO.sub.4,                 bath temperature: 40° C., and                                          current density: 1 A/dm.sup.2.                                              ______________________________________                                    

Thus, a finishing plate layer 4 composed of Rh and having a thickness of1.5 μm was formed. This finishing plate layer 4 had deep white gloss,had a hardness of 850 in Hv and was excellent in abrasion resistance.

A 2.5 μm thick Au--Pt alloy plate layer 5 was formed on the finishingplate layer 4 under the same conditions as in Example 2 (see FIG. 8).

A mask ink of an epoxy resin was screen printed on areas intended to beleft intact of the surface of the Au--Pt alloy plate layer 5, therebyforming a pattern mask 11 as shown in FIG. 9. The whole was immersed ina cyanide-based Au stripping solution to thereby dissolve away theAu--Pt alloy plate layer at the areas other than the above areas coveredby the pattern mask 11.

The pattern mask was peeled off by immersing the whole in a peelingsolution composed of a mixture of a chlorinated hydrocarbon solvent, analcohol, a nonionic surfactant and paraffin wax.

The resultant watch case of two colors of white and gold (multicoloreddecorative member) had the pattern Sa of partial finishing plate layerwith golden tone drawn on part of the surface of the finishing platelayer 4 with deep white tone, thereby exerting a decorative effectenabling rich designs. Further, this multicolored decorative member hadthe same corrosion resistance and heat resistance as had by the whitemember of Example 1.

When it is desired to enlarge the area of the partial finishing platelayer with golden tone on this multicolored decorative member, asuitable process comprises forming a finishing plate layer 4 with whitetone, forming a pattern mask at areas of the finishing plate layer 4where it is desired to leave the white tone while forming a partialfinishing plate layer 5 golden tone at the other areas and finallypeeling the pattern mask off.

Example 8

A primary plate layer 2, an Sn--Cu--Pd alloy plate layer 3, a Ti layer 9and a finishing layer of TiNCO 10 were sequentially formed on a surfaceof a watch case of brass under the same conditions as in Example 6,thereby obtaining a black decorative member D having the layer structureof FIG. 6. Thereafter, a pattern of partial finishing plate layer ofAu--Pt alloy with golden tone was formed on the black finishing layer 10of the black decorative member D in the same manner as in Example 7,thereby obtaining a multicolored decorative member having the layerstructure of FIG. 11.

The resultant watch case of two colors of black and gold (multicoloreddecorative member) had the pattern of partial finishing plate layer withgolden drawn on part of the surface of the finishing layer with glossyblack tone, thereby exerting a fine decorative effect as a whole.Further, this multicolored decorative member had substantially the samecorrosion resistance, heat resistance and adhesion as had by the blackdecorative member of Example 6.

When it is desired to enlarge the area of the partial finishing platelayer with golden tone on this multicolored decorative member, asuitable process comprises the formation of a finishing plate layer withblack tone, the formation of a pattern mask at areas of the finishingplate layer where it is desired to leave the black tone while forming apartial finishing plate layer with golden tone at the other areas andfinally peeling the pattern mask off.

This multicolored decorative member can also be produced by thefollowing process.

That is, first, a golden decorative member having the layer structure ofFIG. 2 is produced. A finishing layer of TiNCO is formed on the surfaceof the finishing plate layer 5 thereof. The surface of areas intended tobe left intact of this finishing layer is covered by a pattern mask. Thewhole is immersed in a 10 to 15% sodium hydroxide solution for a givenperiod of time to thereby peel off the TiNCO at the areas other thanthose covered by the pattern mask. Finally, pattern mask is selectivelypeeled off by immersing the whole in a peeling solution composed of amixture of a chlorinated hydrocarbon solvent, an alcohol, a nonionicsurfactant and paraffin wax.

EFFECT OF THE INVENTION

As apparent from the foregoing description, dissolution of free Ni doesnot occur from the white decorative member comprising the substrate 1,the primary plate layer 2, the Sn--Cu--Pd alloy plate layer 3 and thefinishing plate layer 4 because none of the constituent materialsthereof contains Ni. Further, the interlayer adhesion between platelayers is excellent, so that no peeling phenomenon occurs in the heatingtest. Still further, the white decorative member has excellent corrosionresistance because of the action of the Sn--Cu--Pd alloy plate layer.

Dissolution of free Ni does not occur from both the first goldendecorative member comprising the substrate 1, the primary plate layer 2,the Sn--Cu--Pd alloy plate layer 3 and the finishing plate layer 5 andthe second golden decorative member comprising the substrate 1, theprimary plate layer 2, the Sn--Cu--Pd alloy plate layer 3, the TiN layer7 and the finishing layer 8 because none of the constituent materialsthereof contains Ni.

Dissolution of free Ni does not occur from the black decorative membercomprising the substrate 1, the primary plate layer 2, the Sn--Cu--Pdalloy plate layer 3, the Ti layer 9 and the finishing layer 10 becauseno Ni is contained therein. The outermost black finishing layer of TiNCOhas a very high hardness and is excellent in abrasion resistance.Further, the outermost black finishing layer is strongly bonded with theSn--Cu--Pd alloy plate layer by virtue of the action of the Ti layer.Therefore, the black decorative effect can be exerted for a prolongedperiod of time.

The multicolored decorative member comprising the (a) substrate 1, (b)the primary plate layer 2, (c) the Sn--Cu--Pd alloy plate layer 3, (d)the finishing layer composed of a material selected from the groupconsisting of Pd, Rh, Pt, Au, an Au alloy and TiNCO, and (e) the partialfinishing layer covering part of a surface of the above finishing layer,which partial finishing layer is composed of a material different fromthat of the above finishing layer and has a tone different from that ofthe above finishing layer, has a surface with a tone of, for example,white/gold, white/black or black/gold and exerts a decorative effectenabling rich designs.

The second golden decorative member having both the Ti layer and thefinishing layer formed according to the dry plating technique does notsuffer from dissolution of free Ni because none of the constituentmaterials thereof contains Ni. Moreover, this second golden decorativemember has enhanced abrasion resistance as a whole and ensures aprolonged service life because the golden TiN layer of high abrasionresistance is formed according to the dry plating technique between theoutermost golden layer formed according to the dry plating technique andthe Sn--Cu--Pd alloy plate layer.

The first golden decorative member having the Pd plate layer interposedbetween the Sn--Cu--Pd alloy plate layer 3 and the finishing plate layer5 and the second golden decorative member having the Pd plate layerinterposed between the Sn--Cu--Pd alloy plate layer 3 and the TiN layer7 both exhibit further enhanced interlayer adhesion between platelayers.

The decorative members of the present invention are highly useful asdecorative members of white, gold and black or a tone of a combinationof these which do not induce Ni allergy.

We claim:
 1. A white decorative member comprising:a substrate; a primaryplate layer having a thickness of at least 1 μm and covering a surfaceof the substrate, said primary plate layer being composed of a Cu platelayer or Cu alloy plate layer; an Sn--Cu--Pd alloy plate layer having athickness of at least 0.2 μm and covering a surface of the primary platelayer, said Sn--Cu--Pd alloy plate layer comprising 10 to 20% by weightof Sn, 10 to 80% by weight of Cu and 10 to 50% by weight of Pd asessential components; and a finishing plate layer having a thickness of0.2 to 5 μm and covering the Sn--Cu--Pd alloy plate layer, saidfinishing plate layer being composed of at least one element selectedfrom the group consisting of Pd, Rh and Pt.
 2. The decorative member asclaimed in claim 1, wherein said Cu alloy plate layer is composed of analloy selected from the group consisting of Cu--Sn, Cu--Sn--Zn,Cu--Sn--Pb and Cu--Sn--Cd alloys.
 3. The decorative member as claimed inclaim 2, wherein said Cu alloy plate layer is composed of an alloycomprising 20 to 40% by weight of Sn, 1 to 10% by weight of Zn and abalance of Cu.
 4. A golden decorative member comprising:a substrate; aprimary plate layer having a thickness of at least 1 μm and covering asurface of the substrate, said primary plate layer being composed of aCu plate layer or Cu alloy plate layer; an Sn--Cu--Pd alloy plate layerhaving a thickness of at least 0.2 μm and covering a surface of theprimary plate layer, said Sn--Cu--Pd alloy plate layer comprising 10 to20% by weight of Sn, 10 to 80% by weight of Cu and 10 to 50% by weightof Pd as essential components; and a finishing plate layer having athickness of 0.2 to 5 μm and covering the Sn--Cu--Pd alloy plate layer,said finishing plate layer being composed of an Au plate layer or an Aualloy plate layer which does not contain Ni.
 5. The decorative member asclaimed in claim 4, wherein said Cu alloy plate layer is composed of analloy selected from the group consisting of Cu--Sn, Cu--Sn--Zn,Cu--Sn--Pb and Cu--Sn--Cd alloys.
 6. The decorative member as claimed inclaim 5, wherein said Cu alloy plate layer is composed of an alloycomprising 20 to 40% by weight of Sn, 1 to 10% by weight of Zn and abalance of Cu.
 7. The golden decorative member as claimed in claim 4,wherein a Pd plate layer is interposed between the Sn--Cu--Pd alloyplate layer and the finishing plate layer.
 8. The golden decorativemember as claimed in claim 7, wherein said Pd plate layer is formed by awet plating process.
 9. A golden decorative member comprising:asubstrate; a primary plate layer having a thickness of at least 1 μm andcovering a surface of the substrate, said primary plate layer beingcomposed of a Cu plate layer or Cu alloy plate layer; an Sn--Cu--Pdalloy plate layer having a thickness of at least 0.2 μm and covering asurface of the primary plate layer, said Sn--Cu--Pd alloy plate layercomprising 10 to 20% by weight of Sn, 10 to 80% by weight of Cu and 10to 50% by weight of Pd as essential components; a TiN layer having athickness of 0.1 to 10 μm and covering a surface of the Sn--Cu--Pd alloyplate layer; and a finishing plate layer having a thickness of 0.05 to0.5 μm and covering the TiN layer, said finishing layer being composedof Au alone or an Au alloy which does not contain Ni.
 10. The decorativemember as claimed in claim 9, wherein said Cu alloy plate layer iscomposed of an alloy selected from the group consisting of Cu--Sn,Cu--Sn--Zn, Cu--Sn--Pb and Cu--Sn--Cd alloys.
 11. The decorative memberas claimed in claim 10, wherein said Cu alloy plate layer is composed ofan alloy comprising 20 to 40% by weight of Sn, 1 to 10% by weight of Znand a balance of Cu.
 12. The golden decorative member as claimed inclaim 9, wherein a Pd plate layer is interposed between the Sn--Cu--Pdalloy plate layer and the TiN layer.
 13. The golden decorative member asclaimed in claim 12, wherein said Pd plate layer is formed by a wetplating process.
 14. The golden decorative member as claimed in claim 9,wherein both the TiN layer and the finishing layer are formed by a dryplating process.
 15. A black decorative member comprising:a substrate; aprimary plate layer having a thickness of at least 1 μm and covering asurface of the substrate, said primary plate layer being composed of aCu plate layer or Cu alloy plate layer; an Sn--Cu--Pd alloy plate layerhaving a thickness of at least 0.2 μm and covering a surface of theprimary plate layer, said Sn--Cu--Pd alloy plate layer comprising 10 to20% by weight of Sn, 10 to 80% by weight of Cu and 10 to 50% by weightof Pd as essential components; a Ti layer having a thickness of 0.2 to1.0 μm and covering a surface of the Sn--Cu--Pd alloy plate layer; and afinishing layer having a thickness of 0.5 to 2.0 μm and covering the Tilayer, said finishing layer being composed of TiNCO.
 16. The decorativemember as claimed in claim 15, wherein said Cu alloy plate layer iscomposed of an alloy selected from the group consisting of Cu--Sn,Cu--Sn--Zn, Cu--Sn--Pb and Cu--Sn--Cd alloys.
 17. The decorative memberas claimed in claim 16, wherein said Cu alloy plate layer is composed ofan alloy comprising 20 to 40% by weight of Sn, 1 to 10% by weight of Znand a balance of Cu.
 18. The black decorative member as claimed in claim14, wherein both the Ti layer and the finishing layer are formed by adry plating process.
 19. A multicolored decorative member comprising:asubstrate; a primary plate layer having a thickness of at least 1 μm andcovering a surface of the substrate, said primary plate layer beingcomposed of a Cu plate layer or Cu alloy plate layer; an Sn--Cu--Pdalloy plate layer having a thickness of at least 0.2 μm and covering asurface of the primary plate layer, said Sn--Cu--Pd alloy plate layercomprising 10 to 20% by weight of Sn, 10 to 80% by weight of Cu and 10to 50% by weight of Pd as essential components; a finishing layer havinga thickness of 0.2 to 5.0 μm and covering a surface of the Sn--Cu--Pdalloy plate layer, said finishing layer being composed of a materialselected from the group consisting of Pd, Rh, Pt, Au, an Au alloy andTiNCO; and a partial finishing layer covering part of a surface of thefinishing layer, said partial finishing layer being composed of amaterial which is different from that of the finishing layer and havinga tone which is different from that of the finishing layer.
 20. Thedecorative member as claimed in claim 19, wherein said Cu alloy platelayer is composed of an alloy selected from the group consisting ofCu--Sn, Cu--Sn--Zn, Cu--Sn--Pb and Cu--Sn--Cd alloys.
 21. The decorativemember as claimed in claim 20, wherein said Cu alloy plate layer iscomposed of an alloy comprising 20 to 40% by weight of Sn, 1 to 10% byweight of Zn and a balance of Cu.